The present invention is directed to a novel lamp that can replace a conventional incandescent lamp, such as the miniature incandescent lamp used in automobile stop and tail signals. These incandescent lamps have a standard bulb shape, such as an S8 bulb shape, and a standard base, such as a bayonet or wedge base. The present invention is directed to a novel wedge-based lamp that fits in the socket used by a conventional wedge-based incandescent lamp, such as the S8 wedge-based lamp sold by Osram Sylvania.
A conventional incandescent lamp with a wedge base is shown in FIG. 1. The lamp 10 includes a conventional incandescent bulb 12 and a base part 14 that has faces and fittings 16 that are arranged to mechanically couple the lamp to a wedge-based lamp socket (not shown). An end 18 of the base part 14 includes electrical connections 20 suitable for wedge-based lamp sockets and that lead to the filament in the incandescent bulb 12.
Incandescent lamps are ubiquitous, despite the problems of filament life, bulb breakage and manufacturing issues. A suitable replacement has long been sought that can avoid at least some of these problems; particularly where replacement is complex such as in automobile light fixtures.
Light emitting diodes (LEDs) have long been known as a source of light for visual displays, photoelectronic systems and electro-optical components. LEDs are semiconductor pn-junction radiation sources that emit spontaneous radiation in the visible range. Temperature is a primary stress parameter for LEDs and they should be kept below a defined temperature, say 105° C., for reliable operation. One of the problems with using LEDs as replacements for incandescent lamps has been the heat generated when providing an amount of light equivalent to an incandescent lamp, and the management of that heat in a package that is equivalent in size to the incandescent lamp. This heat problem is exacerbated in some applications by the need to simulate a larger electrical load that is equivalent to that of the incandescent lamp being replaced.